[0001] The present invention claims priority on United States Provisional Application Serial
No.
61/668,658 filed July 6, 2012, which is incorporated herein.
[0002] The present invention is directed to a method for forming an arcuate spring.
BACKGROUND OF THE INVENTION
[0003] Vibration in a vehicle drive train has been a long-standing problem, and a torsional
vibration damper assembly is desirable to neutralize any torsional vibrations emanating
from the vehicle engine which could result in undesirable impact loads, vibration,
noise, etc.
[0004] Torsional vibration damper assemblies have usually comprised straight resilient means,
such as coil springs, which were forcibly bowed through the use of clips, wedges,
spring separators or dividers, or the like to obtain the desired arcuate shape. In
addition, a plurality of shorter straight springs were sometimes substituted for the
longer bowed springs along the path that would have been occupied by the longer bowed
springs. Such configurations, however, were complicated, requiring a plurality of
precise parts to complete the assembly. Thus, such assemblies were difficult to manufacture,
maintain and operate, which translates into a higher product cost.
[0005] To address this past problem, an arcuate spring was developed as disclosed in
US 5,052,664. The '664 patent discloses the use of an arc opening process to form the arcuate
spring. The arc opening process is critical step of the standard arcuate spring manufacturing
process; however, such arc opening process is very time consuming.
[0006] In view of the current state of the art for the formation of arcuate springs, there
is a need for an improved process for forming arcuate springs, arcuate springs having
improved performance, and a process for lowering the manufacturing cost of the arcuate
spring.
SUMMARY OF THE INVENTION
[0007] The present invention is directed to a method for manufacturing an arcuate spring
that addresses the current needs as set forth above.
[0008] The present invention is an improved manufacturing process for forming a spring wherein
all or a portion of the spring has an arcuate shape (e.g., arc shaped, S-shaped, U-shaped,
C-shaped, etc.). As can be appreciated, the various shapes of the spring that can
be formed by the present invention are non-limiting. All these springs that include
at least an arcuate portion will be hereinafter reference to as "arcuate springs".
The improved process eliminates the arc opening process and instead uses an induction
hardening process to form the arc in the spring. The arcuate spring of the present
invention is generally a helically-shaped spring formed of a plurality of coils which
are configured and dimensioned to provide an arcuate shape to the spring in its free
or natural state. As can be appreciated, the spring can have a shape other than a
helical shape. The coils of the arcuate spring are generally free of internal stresses
which would tend to urge the coils into linear alignment. The arcuate spring is generally
designed to have a strength that is sufficient to resiliently absorb and/or release
forces in either arcuate direction along an arcuate path.
[0009] In one non-limiting embodiment of the invention, the arcuate spring is made of a
hardenable or hardened steel. As can be appreciated, the arcuate spring can be formed
of other materials. Generally, the material used to form the arcuate portion of the
spring is a material that can be inductively heated. The arcuate spring is generally
designed to be capable of achieving a Rockwell C hardness of at least about 20 and
up to about 80, and typically between about 40 and 60; however, this is not required.
The arcuate spring generally has a tensile strength of at least 90,000 psi, typically
at least about 100,000 psi, and more typically at least about 190,000 psi; however,
this is not required. The size, shape and length of the arcuate spring are non-limiting.
The cross-section shape and size of the coils of the spring are non-limiting. The
arc radius of the spring is non-limiting.
[0010] In another and/or alternative non-limiting embodiment of the invention, there is
provided a method for making an arcuate spring by initially forming a straight spring;
prestressing the spring to an arcuate shape; heat treating the spring by induction
heating at elevated temperatures for a sufficient time to relieve stresses in the
spring and to form an arcuate spring; and then cooling the arcuate spring to lower
(e.g., ambient) temperatures. The spring is generally prestressed by use of a fixture.
The type of fixture is non-limiting. The spring can be heat treated subsequent to
being prestressed by the fixture and/or heated prior to being prestressed by the fixture.
Generally, the spring is heated subsequent to being prestressed by the fixture. The
heat treating step generally includes heating one or more portions of the spring by
an induction heating process. Optionally, additional types of heat treating processes
can be used to heat one or more portions of the spring. The heat treating step includes
a step of cooling the spring. In one non-limiting arrangement, the cooling step includes
quenching the spring into a fluid (e.g., air, gas, liquid, etc.). In one non-limiting
example, the quench fluid is a liquid (e.g., water, oil, water and oil mixture, etc.).
In another non-limiting example, the quench fluid is a gas (e.g., nitrogen argon,
air, etc.). The spring during the cooling process is generally rapidly cooled (e.g.,
cooled within 0.01-5 minutes, etc.) by the quench fluid to a temperature that is generally
from +150°F to -50F of the ambient temperature (e.g., 60-90F). In one non-limiting
example, the spring during the cooling process is rapidly cooled (e.g., cooled within
0.01-2 minutes) by the quench fluid to a temperature that is generally about ±30F
of the ambient temperature (e.g., 60-90°F). Generally the spring is released from
the fixture after and/or during the quenching step.
[0011] As mentioned above, the present invention is an improvement over prior art methods
for forming an arcuate spring. Current prior art processes for forming an arcuate
spring involve the steps of:
- 1. Coiling the wire to form a straight helical spring;
- 2. Stress relieving the formed straight helical spring;
- 3. Shot peening straight helical spring;
- 4. Grinding the ends of the straight helical spring;
- 5. Shot peening the straight helical spring a second time;
- 6. Pre-heating the straight helical spring;
- 7. Bending the helical spring in a fixture;
- 8. Heating the bent helical spring in an oven for over 20 minutes while in the fixture;
- 9. Quenching the heated helical spring; and,
- 10. Removing the quenched helical spring from the fixture.
[0012] The present invention is a significant improvement over the prior art process for
forming an arcuate spring. The process of the present invention involves the steps
of:
a. Coiling the wire to form a straight spring;
b. Heating the spring by induction heating prior to bending the spring in a fixture;
b. Bending the heated spring in the fixture;
d. Quenching the heated spring; and,
e. Removing the quenched spring from the fixture.
[0013] The forming process in accordance with the present invention is fundamentally different
from prior arcuate spring forming processes in that the spring is first heated by
induction heating prior to the spring being placed in a fixture. As can be appreciated,
the spring could be placed in a fixture prior to and during heating. When the spring
is inductively heated, the spring is generally heated while the spring is a straight
spring. The induction heating of the spring generally takes less than about 5 minutes,
typically less than about 2 minutes, more typically less than about 1 minute, and
yet more typically less than about 30 seconds; however, other time periods can be
used. The heating time using an induction heating process is significantly less than
convention heating time period that occurred in an oven, which prior heating times
were in excess of 10 minutes, and typically at least 20 minutes. After the spring
is inductively heated when in a straight shape, the heated straight spring is generally
formed in the fixture into an arcuate shape in less than about 5 minutes after being
inductively heated, typically less than about 2 minutes after being inductively heated,
more typically less than about 1 minute after being inductively heated, and yet more
typically less than about 30 seconds after being inductively heated; however, other
time periods can be used. The spring that was heated and hardened by the process in
accordance with the present invention exhibited improved residual stress rates as
compared to springs that were heated in a traditional heating oven.
[0014] One or more additional process steps can be used for form the arcuate spring of the
present invention. Such optional additional steps include:
- i. Stress relieving the formed spring prior and/or after induction heating.
- ii. Shot peening the spring one or more times prior and/or after induction heating.
- iii. Pre-heating the spring prior to induction heating.
- iv. Grinding the ends of the spring prior and/or after induction heating.
- v. Attaching an end cap to one or more ends of spring with or without the grinding
of the ends of the spring.
[0015] One non-limiting object of the present invention is to provide an improved process
for forming arcuate springs.
[0016] Another and/or alternative non-limiting object of the present invention is to provide
an improved process for forming arcuate springs that have improved performance.
[0017] Still another and/or alternative non-limiting object of the present invention is
to provide an improved process for forming arcuate springs that lowers the manufacturing
cost of the arcuate springs.
[0018] Yet another and/or alternative non-limiting object of the present invention is to
provide an improved process for forming arcuate springs that reduce risk of inclusion
failures with better residual stress profile induced by the induction heat treatment.
[0019] Still yet another and/or alternative non-limiting object of the present invention
is to provide an improved process for forming arcuate springs that increase material
hardness, generating a high fatigue arcuate spring (i.e., improved fatigue properties).
[0020] Another and/or alternative non-limiting object of the present invention is to provide
an improved process for forming arcuate springs that can also generate unique spring
shapes (e.g., S-shapes, C-shapes, U-shapes, etc.).
[0021] Still another and/or alternative non-limiting object of the present invention is
to provide an improved process for forming arcuate springs that have improved mechanical
properties.
[0022] Yet another and/or alternative non-limiting object of the present invention is to
provide an improved process for forming arcuate springs that reduces the time for
forming the arcuate springs.
[0023] Still yet another and/or alternative non-limiting object of the present invention
is to provide an improved process for forming arcuate springs that uses induction
heating to form the arcuate springs.
[0024] Another and/or alternative non-limiting object of the present invention is to provide
an improved process for forming arcuate springs that uses end caps on one or more
ends of the spring so as to eliminate or reduce the need to grind one or both ends
of the arcuate springs.
[0025] Still another and/or alternative non-limiting object of the present invention is
to provide an improved process for forming arcuate springs that includes the steps
of a) coiling the wire to form a straight spring; b) heating the spring by induction
heating; c) bending the heated spring in a fixture; d) quenching the heated spring;
and, e) removing the quenched spring from the fixture.
[0026] Yet another and/or alternative non-limiting object of the present invention is to
provide an improved process for forming arcuate springs that includes one or more
additional/optional process steps that include i) stress relieving the formed spring
prior and/or after induction heating; ii) shot peening the spring one or more times
prior and/or after induction heating; iii) pre-heating the spring prior to induction
heating; iv) grinding the ends of the spring prior and/or after induction heating;
and/or v) attaching an end cap to one or more ends of spring with or without the grinding
of the ends of the spring.
[0027] Still yet another and/or alternative non-limiting object of the present invention
is to provide an arcuate spring having a plurality of coils which are configured and
dimensioned to provide an arcuate shape to the spring and being substantially free
of internal stresses which would tend to urge the coils into linear alignment.
[0028] Another and/or alternative non-limiting object of the present invention is to provide
an arcuate spring having a plurality of coils which are configured and dimensioned
to provide an arcuate shape to the spring and having an end cap connected to one or
more ends of the spring with or without the grinding of the ends of the spring.
[0029] Still another and/or alternative non-limiting object of the present invention is
to provide an arcuate spring that may or may be formed by the use of induction heat
treatment.
[0030] Yet another and/or alternative non-limiting object of the present invention is to
provide an arcuate spring having increased fatigue life and better material properties
due to induction heat treatment.
[0031] These and other objects and advantages will become apparent to those skilled in the
art upon the reading and following of this description taken together with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Reference may now be made to the drawings, which illustrates non-limiting embodiments
of the present invention;
FIG. 1 is an iso view of the arcuate spring in accordance with the present invention;
FIG. 2 is a front view of the arcuate spring of FIG. 1;
FIG. 3 is a cross-sectional view along lines 3-3 of FIG. 2; and,
FIG. 4 is a cross-sectional view along lines 4-4 of FIG. 2;
FIG. 5 is a front elevation view of a spring fixture in accordance with the present
invention;
FIG. 6 is a front elevation view of an end cap in accordance with the present invention;
FIG. 7 is a top view of the end cap of FIG. 6; and,
FIGS. 8-15 are side views of several non-limiting arcuate shaped springs in accordance
with the present invention.
DESCRIPTION OF NON-LIMITING EMBODIMENTS
[0033] Referring now to FIGS. 1-15, which illustrate non-limiting embodiments of the present
invention, there is provided an arcuate spring and method for manufacturing the arcuate
spring. The arcuate spring can be used in a variety of different application. One
non-limiting application is the use of the arcuate spring in a torsional vibration
damper assembly as illustrated in
US 5,052,664, which is incorporated herein by reference. The operation of the torsional vibration
damper assembly with the arcuate helical spring will be smoother than the operation
of a torsional vibration damper assembly which utilizes forcibly bowed straight springs.
A forcibly bowed straight spring is constantly experiencing internal stresses which
tend to straighten the spring. Thus, the forcibly bowed straight spring rubs against
and interferes with the sides of torsional vibration damper assembly, thus inhibiting
smooth operation. The arcuate spring when used on a torsional vibration damper assembly
will also provide improved attenuation or damping of spring vibrations than the conventional
vibration damper which utilizes straight springs for the same reasons as specified
above. In addition, the compression of the arcuate spring to a "solid" configuration,
i.e., where each coil contacts each adjacent coil, operates as a stop in the system
independently of the use of other means. Undesirable stressing in the arcuate helical
spring will also be avoided due to the spring's arcuate shape, and by use of induction
heating of the spring during the forming process of the spring, thereby improving
the efficient use of the vibration damper assembly. A straight spring forcibly bowed
upon assembly experiences stresses due to the unnatural installation that are opposite
in direction to the stresses which arise in the spring through use in the torsional
vibration damper assembly. Springs installed in this manner experience stresses in
one direction with the unit at rest. As torque is applied to the unit and increased,
the springs deflect until at a point where these stresses diminish to zero. Further
loading and deflection results in these stresses increasing in the opposite direction.
This bidirectional stressing reduces the stress allowable to avoid excessive relaxation
or breakage that can be experienced by the spring in service. In contrast, the body
of the arcuate spring will experience only normal uni-directional stressing because
the arcuate spring is received in the housing in its natural arcuate state. Thus,
the arcuate spring will not be overly stressed, thereby increasing the useful capacity
and service life of the vibration damper assembly. The durability of the vibration
damper assembly can also be increased due to the reduction in the number of springs
required for operation. Spring ends have historically been subject to bending fatigue
breakage near the tips of the ground end coils. The present invention avoids the past
need to grind the ends of the spring when the novel end caps of the present invention
are used. In conventional torsional vibration damper assemblies, a plurality of straight
springs are employed, thereby increasing the number of ground ends and providing greater
opportunities for failure. However, since a single arcuate spring may replace a plurality
of shorter straight springs, the number of spring ends is reduced. Also, those remaining
spring ends may be reinforced by making use of the saved space that results from the
minimization of components in the damper. Thus, the number of potential failure locations
is reduced and the life and durability of the assembly can be increased by use of
the arcuate spring.
[0034] Referring now to FIGS. 1-4 and 8-15, the arcuate spring 10 of the present invention
can be made by various processes. Figs. 1-4 and 15 illustrate an arc shaped spring
and Figs. 8-14 illustrate types of S-shaped springs (Figs. 8-9 & 14), a C-shaped spring
(Figs. 10 & 13) a U-shaped spring (Fig. 11) and a wave-shaped spring (Fig. 12). The
solid lines through the springs illustrated in Figs. 8-11 are merely is a line along
the central axis of the spring to illustrate the shape of the spring and does not
represent any type of structure of the spring. As can be appreciated, the spring in
accordance with the present invention can have other shapes that include an arcuate
shape. In one non-limiting method, a conventionally coiled straight spring is formed
by traditional helical spring manufacturing techniques. Such techniques include beginning
with annealed or pre-hardened and tempered material of any required cross section.
Current materials that can be used include, but are not limited to, 1070, 6150, modified
6150, and 9254 steels, as processed into suitable quality spring wire. Generally,
round cross-section, pre-hardened and tempered (Rc 45-55) 6150 steel can be used.
As can be appreciated, other materials can be used. As can also be appreciated, the
material need not be annealed, pre-hardened and/or tempered. As can further be appreciated,
the material can have different Rc values.
[0035] After the spring is formed in a straight helical shape, the spring is then heat treated
by an induction heating process. For example, in the case of pre-hardened and tempered
6150 steel, the heat treatment by induction heating would be less than about 1 minute
and the metal would be heated to at least about 700°F. Any standard induction heating
process can be used.
[0036] After the spring is inductively heated, the straight helical spring is bent and forced
into an arc by use of a fixture. Any type of fixture can be used. Generally the fixture
is formed of metal material and/or a ceramic material; however, other or additional
materials can be used. One non-limiting fixture arrangement is illustrated in FIG.
5. The fixture arrangement 20 includes a clamping arrangement having two arcuate profile
surfaces 30, 40 that are positioned on opposite sides of the spring 10. As such, when
the two arcuate profile surfaces of the clamping arrangement are drawn together while
the straight spring is positioned between the two arcuate profile surfaces, the two
arcuate profile surfaces upon contact with the sides of the spring will cause the
spring to bend into the desired arcuate shape. The materials used to the form the
two arcuate profile surfaces is non-limiting. For example, when an S-shaped spring
(See Figs. 8-9 &14) is to be formed, the two arcuate profile surfaces can have an
S-shape profile. The two arcuate profile surfaces can also have shapes for forming
C-shaped spring (See Figs. 10 & 13), U-shaped springs (See Fig. 11), wave-shaped springs
(Fig. 12), etc. Generally the radius of curvature of arcuate profile surface 40 that
contacts a first side of the spring is greater than the radius of curvature of the
arcuate profile surface 30 that contacts the opposite side of the spring. Arcuate
profile surface 30 is illustrated as being mounted in a fixed position by mounts 32,
34; however, this is not required. Arcuate profile surface 40 is illustrated as being
moveable by arms 42, 44 between a clamped and unclamped position; however, this is
not required. As can be appreciated, either or both arcuate profile surfaces can be
designed to be movable. As can be appreciated, the fixture can have other forms. For
example, the fixture can include the use of a close-fitting curved rod or pin of a
different free angle and arc radius than the desired free angle and arc radius of
the finished arcuate spring. This close-fitting curved rod or pin is inserted into
the spring. As can be appreciated, other fixtures can be used to cause the spring
to be bent into a desired arc prior to the heating process (e.g., bowed or curved
tube, die, drum or mandrel about which the spring, etc.).
[0037] After the heated spring is formed into the arcuate shaped by the fixture, the heated
spring is quenched (e.g., air and/or liquid quench) to a temperature of about ±150°F
of ambient temperature, and typically about ±30°F of ambient temperature in less than
about 3 minutes, typically less than about 2 minutes, and more typically less than
about 1 minute; however, other quench times can be used. If the quench fluid is a
liquid, the liquid can be water at about ambient temperature; however, other water
temperatures can be used. The quenching process generally occurs within about 120
seconds (e.g., ≥60 seconds; ≥30 seconds, etc.) after the spring is formed in the fixture
and/or after induction heating process has been completed. The water, when used, can
include a soluble oil and/or other type of polymer material; however, this is not
required. After the quenching process is completed, the spring is removed from the
fixture (e.g., the two arcuate profile surfaces are again separated from one another,
rod removed, etc.), at which time the spring retains an arcuate configuration, free
or substantially of any internal stresses which would tend to straighten the spring.
In one non-limiting process, the step of induction heating is less than about 5 minutes
(e.g., 0.1-3 minutes, 0.1-2 minutes, 0.1-1 minute, etc.), the step of bending the
heated spring in the fixture is completed in less than about 5 minutes (e.g., 0.01-2
minutes, 0.01-1 minutes, 0.01-0.5 minute, etc.) after the step of induction heating,
and the step of quenching the heated spring is completed in less than about 5 minutes
(e.g., 0.1-3 minutes, 0.1-2 minutes, 0.1-1 minute, etc.) after the bending said heated
spring in said fixture.
[0038] One or more ends of the spring can be optionally ground prior to and/or after the
induction heating process; however, this is not required. The grinding step can be
eliminated by the use of the end caps 50 as illustrated in FIGS. 6-7. The end cap
includes a base portion 70 and a nose 60. The nose is designed to be at least partially
inserted into the interior of the spring coils. The base portion has a generally circular
cross-sectional shape; however, the base portion can have other shapes. The cross-section
size and shape of the base portion is generally selected such that the base portion
cannot be fully inserted into the interior of the spring coils; however, this is not
required. The thickness of the base portion is non-limiting. The nose portion 60 is
illustrated as having a non-uniform cross-sectional size; however, this is not required.
The nose portion is illustrated has having a generally circular cross-sectional shape;
however, the nose portion can have other shapes. The nose portion has an upper nose
portion 62 and a lower nose portion 64; however, this is not required. The top section
of the upper nose portion can optionally include a taper 61. The upper nose portion
62 is illustrated as having a smaller cross-sectional size than lower nose portion
64. Generally lower nose portion 64 has a cross-section size and shape such that the
lower nose portion 64 engages the inner surfaces of the interior of the spring coils
so as to facilitate in secure the end cap to the spring; however, this is not required.
A transition 65 can optionally be formed between the upper nose portion 62 and a lower
nose portion 64. The transition, when used, can optionally have a tapered or sloped
form. The upper surface of the base portion optionally includes a threading lip 72
and/or a stop 68. The threading lip, when used, can have a narrow front portion as
illustrated in FIG. 7 which is designed to engage the inner surfaces of the interior
of the spring coils so that the end cap can be threaded into the spring; however,
this is not required. The stop, when used, is designed to limit the further threading
of the end cap onto the spring. As the end cap is threaded onto the spring, the end
12 of the spring will engage the stop and thereby prevent further threading of the
end cap into the spring. The threading lip is illustrated as increasing in thickness
from the narrow front portion to the stop 68 as illustrated in FIG. 6. The end cap
can be formed of any type of material. The end cap, when used, can be used to extend
the life of the spring by protecting the ends of the spring. When the ends of the
spring are not properly ground, undesired stresses can be applied to the spring ends
during use of the spring, thereby cause premature failure of the spring. The use of
the end caps on the spring can reduce or eliminate such undesired stresses on the
ends of the spring and therefore extend the usable life of the spring.
[0039] One or more additional process steps can be used for form the arcuate spring of the
present invention. Such optional additional steps include:
- i. Stress relieving the formed spring prior and/or after induction heating.
- ii. Shot peening the spring one or more times prior and/or after induction heating.
- iii. Pre-heating the spring prior to induction heating.
[0040] It will thus be seen that the objects set forth above, among those made apparent
from the preceding description, are efficiently attained, and since certain changes
may be made in the constructions set forth without departing from the spirit and scope
of the invention, it is intended that all matter contained in the above description
and shown in the accompanying drawings shall be interpreted as illustrative and not
in a limiting sense. The invention has been described with reference to preferred
and alternate embodiments. Modifications and alterations will become apparent to those
skilled in the art upon reading and understanding the detailed discussion of the invention
provided herein. This invention is intended to include all such modifications and
alterations insofar as they come within the scope of the present invention. It is
also to be understood that the following claims are intended to cover all of the generic
and specific features of the invention herein described and all statements of the
scope of the invention, which, as a matter of language, might be said to fall therebetween.
[0041] Further embodiments of the invention are:
- 1. An arcuate spring having a plurality of coils configured and dimensioned to provide
an arcuate shape to the spring in its free state and being substantially free of internal
stresses which would tend to urge said coils into linear alignment, said spring including
first and second ends, said first end including an end cap connected to said first
end.
- 2. The arcuate spring as defined in embodiment 1, wherein said second end including
an end cap connected to said second end.
- 3. The arcuate spring as defined in embodiment 1, wherein said end cap including a
base portion and a nose, said nose designed to be at least partially inserted into
an interior of said coils of said spring coils, said base portion cross-section size
and shape such that said base portion cannot be fully inserted into said interior
of said spring coils.
- 4. The arcuate spring as defined in embodiment 2, wherein said end cap including a
base portion and a nose, said nose designed to be at least partially inserted into
an interior of said coils of said spring coils, said base portion cross-section size
and shape such that said base portion cannot be fully inserted into said interior
of said spring coils.
- 5. The arcuate spring as defined in embodiment 3, wherein said nose and said base
portion of said end cap having a generally circular cross-sectional shape.
- 6. The arcuate spring as defined in embodiment 4, wherein said nose and said base
portion of said end cap having a generally circular cross-sectional shape.
- 7. The arcuate spring as defined in embodiment 3, wherein said nose portion has a
non-uniform cross-sectional size, said nose portion having an upper nose portion that
has a smaller cross-sectional size than a lower nose portion.
- 8. The arcuate spring as defined in embodiments 4-6, wherein said nose portion has
a non-uniform cross-sectional size, said nose portion having an upper nose portion
that has a smaller cross-sectional size than a lower nose portion.
- 9. The arcuate spring as defined in embodiment 3, wherein said upper surface of said
base portion includes a threading lip and a stop, said threading lip designed to engage
said inner surface of said spring coils so that said end cap can be threaded into
the spring, said stop designed to limit further threading of said end cap onto said
spring.
- 10. The arcuate spring as defined in embodiments 4-8, wherein said upper surface of
said base portion includes a threading lip and a stop, said threading lip designed
to engage said inner surface of said spring coils so that said end cap can be threaded
into the spring, said stop designed to limit further threading of said end cap onto
said spring.
- 11. The arcuate spring as defined in embodiment 1, wherein at least a portion of said
spring includes an arc-shape, S-shape, C-shape, wave-shape or U-shape.
- 12. The arcuate spring as defined in embodiments 2-10, wherein at least a portion
of said spring includes an arc-shape, S-shape, C-shape, wave-shape or U-shape.
- 13. A method for forming an arcuate spring comprising the steps of:
- a. Coiling a wire to form a non-arcuate spring;
- b. Heating said non-arcuate spring by induction heating prior to bending said non-arcuate
spring in a fixture;
- c. Bending said heated spring in said fixture; and,
- d. Quenching said heated spring.
- 14. The method as defined in embodiment 13, including the step of removing said quenched
spring from said fixture after said quenching step.
- 15. The method as defined in embodiment 13, wherein said step of induction heating
is less than about 5 minutes, said step of bending said heated spring in said fixture
is completed in less than about 5 minutes after said step of induction heating, said
step of quenching said heated spring is completed in less than about 5 minutes after
said bending said heated spring in said fixture.
- 16. The method as defined in embodiment 14, wherein said step of induction heating
is less than about 5 minutes, said step of bending said heated spring in said fixture
is completed in less than about 5 minutes after said step of induction heating, said
step of quenching said heated spring is completed in less than about 5 minutes after
said bending said heated spring in said fixture.
- 17. The method as defined in embodiment 13, wherein said fixture includes a clamping
arrangement having two arcuate profile surfaces, at least one of said arcuate profile
surfaces designed to movable between a clamped and unclamped position.
- 18. The method as defined in embodiments 14-16, wherein said fixture includes a clamping
arrangement having two arcuate profile surfaces, at least one of said arcuate profile
surfaces designed to movable between a clamped and unclamped position.
- 19. The method as defined in embodiment 13, including the step of applying an end
cap on at least one end of said spring after said step of quenching, said end cap
including a base portion and a nose, said nose designed to be at least partially inserted
into an interior of said coils of said spring coils, said base portion cross-section
size and shape such that said base portion cannot be fully inserted into said interior
of said spring coils.
- 20. The method as defined in embodiments 14-18, including the step of applying an
end cap on at least one end of said spring after said step of quenching, said end
cap including a base portion and a nose, said nose designed to be at least partially
inserted into an interior of said coils of said spring coils, said base portion cross-section
size and shape such that said base portion cannot be fully inserted into said interior
of said spring coils.
- 21. The method as defined in embodiment 19, wherein said upper surface of said base
portion includes a threading lip and a stop, said threading lip designed to engage
said inner surface of said spring coils so that said end cap can be threaded into
the spring, said stop designed to limit further threading of said end cap onto said
spring.
- 22. The method as defined in embodiment 20, wherein said upper surface of said base
portion includes a threading lip and a stop, said threading lip designed to engage
said inner surface of said spring coils so that said end cap can be threaded into
the spring, said stop designed to limit further threading of said end cap onto said
spring.
- 23. The method as defined in embodiment 13, wherein at least a portion of said spring
includes an arc-shape, S-shape, C-shape, wave-shape or U-shape.
- 24. The method as defined in embodiments 14-22, wherein at least a portion of said
spring includes an arc-shape, S-shape, C-shape, wave-shape or U-shape.
1. A method for forming an arcuate spring comprising the steps of:
a. providing a coiled wire to form a spring having a non-arcuate shape, said spring
having a longitudinal length, a plurality of coils and a central axis that pass through
said plurality of coils, at least a portion of said spring configured and dimensioned
to provide a straight shape along said longitudinal length and said central axis of
said spring while said spring is in its free state and being substantially free of
internal stresses, said spring including first and second ends;
b. heating said spring by induction heating;
c. positioning said heated spring in a fixture while said spring is in a heating state
from said induction heating, said fixture including a clamping arrangement having
first and second arcuate profile surfaces that are positioned on opposite sides of
said heated spring, at least one of said first and second arcuate profile surfaces
configured to be movable between a clamped and unclamped position;
d. bending said heated spring in said fixture by moving at least one of said first
and second arcuate profile surfaces from said unclamped position to said clamped position
thereby causing a distance between said first and second arcuate profile surfaces
to reduce and thereby cause said heated spring while said heated spring is in a heated
state to engage said arcuate profile surfaces and thereby cause said heated spring
to bend and conform to a shape of a space between said first and second arcuate profile
surfaces when in said clamped position such that said central axis of said heated
spring has a non-linear shape along a longitudinal length of said spring, said spring
being inserted into said fixture and being bent in said fixture after completion of
said induction heating step;e. quenching said heated spring in said fixture while
said first and second arcuate profile surfaces are in said clamped position and said
heated spring is positioned between said first and second arcuate profile surfaces
and said central axis of said spring is in said non-linear shape;
f. moving at least one of said first and second arcuate profile surfaces to said unclamped
position after said spring is quenched; and,
g. removing said spring from said fixture after said quenching step and at least one
of said first and second arcuate profile surfaces are moved to said unclamped position,
said spring maintaining said arcuate shape along said longitudinal length and said
central axis of said spring after said spring is quenched and removed from said fixture,
said spring having said arcuate shape along said longitudinal length and said central
axis of said spring when in its free state and said spring being substantially free
of internal stresses.
2. The method as defined in claim 1, wherein said step of induction heating is less than
about 5 minutes, said step of bending said heated spring in said fixture is completed
in less than about 5 minutes, said step of bending said heated spring occurring after
said step of induction heating is completed, said step of quenching said heated spring
is completed in less than about 5 minutes after said bending of said heated spring
in said fixture.
3. The method as defined as defined in any one of claims 1 or 2, wherein at said first
arcuate profile surfaces is movable toward and away from said second arcuate profile
in a direction that is tangential to said central axis of said non-arcuate spring.
4. The method as defined as defined in any one of claims 1 to 3, including the step of
applying an end cap on at least one end of said spring after said step of quenching,
said end cap including a base portion and a nose, said nose configured to be at least
partially inserted into an interior of said coils of said spring coils, said base
portion having a cross-section size and shape such that said base portion cannot be
fully inserted into said interior of said spring coils.
5. The method as defined as defined in claim 4, wherein an upper surface of said base
portion includes a threading lip and a stop, said threading lip configured to engage
an inner surface of said spring coils so that said end cap can be threaded into the
spring, said stop configured to limit further threading of said end cap onto said
spring, said stop positioned at an end of said threading lip and extending upwardly
from said threading lip.
6. The method as defined as defined in any one of claims 1 to 5, wherein at least a portion
of said shape of said space between said first and second arcuate profile surfaces
when in said clamped position is selected from the group consisting of an arc-shape,
a S-shape, a C-shape, a wave-shape or U-shape to thereby cause at least a portion
of said spring to have an arc-shape, a S-shape, a C-shape, a wave-shape or a U-shape.
7. The method as defined as defined in any one of claims 1 to 6, including one or more
of the following steps selected from the group consisting of a) stress relieving said
spring prior said step of heating, b) stress relieving said spring after said step
of heating, c) shot peening said spring prior said step of heating, d) shot peening
said spring after said step of heating, e) pre-heating said spring prior to said step
of heating, f) grinding at least one end of said spring prior to said step of heating,
and g) grinding at least one end of said spring after to said step of heating.
8. The method as defined in any one of claims 1 to 7, wherein said step of bending includes
causing a distance between said first and second arcuate profile surfaces to reduce
and thereby cause said heated spring to engage said arcuate profile surfaces and thereby
cause said heated spring to bend and conform to a shape of a space between said first
and second arcuate profile surfaces when in said clamped position; and/or wherein
said step of removing including moving at least one of said first and second arcuate
profile surfaces to said unclamped position after said spring is quenched.